Free Tools

1. Anchor Text Over Optimization Tool

http://www.removeem.com/ratios.phpLink Research, Technical SEO
Worried about Google's Penguin algorithm hitting you for over-optimized anchor text? Simply type in your URL for a full report of which links might raise flags.

2. Bing Webmaster Tools

http://www.bing.com/toolbox/webmasterTools Suite, Diagnostic
Similar in function to Google Webmaster Tools, Bing offers a suite of interesting research tools and resources for webmasters.

3. Bitly

https://bitly.com/Social, Analytics
Most people use Bitly for URL shortening, but the real power of this platform comes from its analytics.

4. Boomerang

http://www.boomeranggmail.com/Email, Productivity
Boomerang lets you follow up on emails, even when you forget. Great for link building or any time you send a lot of emails.

5. Buffer

https://bufferapp.com/Social
Optimize your online social media sharing. Buffer allows you to share with your audience at the optimal times for greater visibility.

6. BuiltWith

http://builtwith.com/Competitive Intelligence
Use BuiltWith to discover what technology nearly any website was, well, built with. Great for competitive intelligence as well.

7. Buzzstream Tools Suite

http://tools.buzzstream.com/link-buildingLink Building, Tools Suite, Email
Most people know Buzzstream as an outreach platform, but they also offer a number of free link-building tools. This company gets it.

8. Caption Tube

http://captiontube.appspot.com/Video
Free and easy resource used to create captions for YouTube. Helps with usability and offers viewers a readable transcript.

14. Easel.ly

15. Email Format

http://email-format.com/Email, Productivity
Email Format helps you find the proper structure for thousands of companies and organizations across the web.

16. FindPeopleonPlus

http://www.findpeopleonplus.com/Social
The ultimate Google+ directory that's great for research, outreach, and link building. Sort by keywords, profession, country, and more.

17. Frobee Robots.txt Checker

http://www.frobee.com/robots-txt-checkRobots.txt, Technical SEO
Many robots.txt files contain hidden errors not easily visible to humans. Run your file through this tool and you never know what you'll discover.

18. GetListed

https://getlisted.org/Local, Moz
This awesome local SEO tool scores your local SEO visibility and gives you actionable next steps to raise your score.

40. Rank Checker for Firefox

41. Rapportive

http://rapportive.com/Email, Link Building, Productivity
Rapportive works with your Gmail inbox to give you near-instant rich contact information for almost everyone you want to reach. A must-have for marketers.

42. Remove Duplicate Items

http://ontolo.com/tools-remove-duplicatesProductivity
Ontolo offers a suite of link building software and a few helpful productivity tools for link builders. The remove duplicates tool solves a common problem.

43. Robots.txt Checker

44. Schema Creator

http://schema-creator.org/Structured Data, Technical SEO
Everyone loves using Schema.org, but the microformats are difficult to write by hand. This generator from the folks at Raven simplifies the task.

47. SEO Toolbar

http://tools.seobook.com/seo-toolbar/Tools Suite, Toolbar, Technical SEO
On of the most popular tools available, The SEO Toolbar puts a ton of information at your fingertips including backlinks and competitive research.

48. SEO Tools for Excel

http://nielsbosma.se/projects/seotools/Tools Suite, Analytics, Social
You don't need to be an Excel ninja to use Niels Bosma's SEO Tools for Excel. This plugin does so many things many SEOs won't work without it.

49. SEOgadget Links API

http://seogadget.com/api/API, Link Research
The SEOgadget Links API lets you easily gather not only backlink data but contact information as well. A huge time saver.

50. SEOgadget Tools

http://seogadget.com/tools/Tools Suite
This suite of tools from the Gadget lab includes several Excel plugins, a content strategy generator, and more.

56. Social Authority API

https://followerwonk.com/social-authorityAPI, Social
How much reach and social authority do your followers have? How about the people you're trying to connect with? The free Social Authority API will tell you.

57. Social Crawlytics

https://socialcrawlytics.com/Social, Analytics
Social Crawlytics allows you to conduct competitive research by showing you your competitors' most-shared content. Lots of other features as well.

58. Social Mention

http://www.socialmention.com/Social
Social mention offers real-time social media search and analysis. Enter a search term and see who's sharing what, right now.

59. Text Cleaner

http://www.textcleanr.com/Content
Some of the best tools solve the simplest problems. Text cleaner cleans up all kinds of text formatting when copying and pasting between aplications.

60. Ubersuggest

http://ubersuggest.org/Keyword Research
Every SEO loves Ubersuggest for its ease of use and wealth of keyword research ideas. Utilizing the power of Google Suggest, it returns hundreds of potential results.

61. URI Valet

62. Virante SEO Tools

http://www.virante.org/seo-toolsTools Suite
Virant offers a number of high quality SEO tools to the public. These are often the same tools developed for the Virant team, opened up for public use.

63. Wayback Machine

http://archive.org/web/web.phpCompetitive Intelligence
Want to see the history of your website or your competitor's site? The Wayback Machine allows you to step back in time and track important changes.

67. Xenu's Link Sleuth

http://home.snafu.de/tilman/xenulink.htmlDiagnostic, Technical SEO
Winner of the ugliest-SEO-tool-on-the-planet award, Xenu is also one of the most useful. Crawl entire sites, find broken links, create sitemaps, and more.

68. XML-Sitemaps.com

http://www.xml-sitemaps.com/Sitemaps
XML-Sitemaps offers probably the easiest sitemap creation solution anywhere. Great for smaller sites when you need a sitemap in minutes.

69. Yahoo Pipes

http://pipes.yahoo.com/pipes/Content, Productivity
A great mashup tool that combines different feeds into content and other magical creations. Used for link building and whatever you can dream of.

70. Yoast WordPress SEO Plugin

http://yoast.com/wordpress/seo/Technical SEO
If you could only choose one WordPress plugin for you site, the first would be from Yoast, and so would the second. This one sets the standard.

71. YouTube Analytics

Free and Paid

72. Ahrefs

https://ahrefs.com/Link Research, Link Building
One of the more popular link research tools, Ahrefs offers a large index and nice anchor text distribution charts. Mostly a paid tool, but they offer some free data.

73. Banana Tag

http://bananatag.com/Email
Banana Tag allows you to track your emails after you send them. For example, check your email open rates from Gmail.

74. CloudFlare

https://www.cloudflare.com/Speed
How do they make CloudFlare free? It works both as a CDN and a security service to provide your website with speed and safety.

75. Followerwonk

https://followerwonk.com/Social, Analytics, Moz
Perhaps the coolest thing about Followerwonk is the ability to track your followers. Smart SEOs also use it for outreach and research.

76. Keyword Eye

http://www.keywordeye.com/Keyword Research
Keyword eye adds a twist to keyword research by adding rich visualizations — essential when you want to move beyond keywords to valuable concepts.

77. KnowEm

http://knowem.com/Social
KnowEm allows you to check 100's of social profiles at once to check availability. Looking for the perfect brand name? Check KnowEm first.

78. Majestic SEO

http://www.majesticseo.com/Link Research, Competitive Intelligence, Link Building
You've probably seen Majestic SEO link charts all over the Internet. Great crawling technology combined with several free options make for great link research.

79. Majestic SEO API

80. MozBar

http://moz.com/tools/seo-toolbarTools Suite, Toolbar, Moz
The standard SEO toolbar for legions of marketers, the MozBar allows you to perform over 50 key tasks right from your browser. Highly recommended.

81. Mozscape API

http://moz.com/products/apiAPI, Link Research, Moz
Companies everywhere incorporate the Mozscape API into their own products, but it's also available to individuals, and much of the data is free.

82. nTopic

http://www.ntopic.org/Content
nTopic is one of the few proven methods for giving your content a relevancy score and offering keyword suggestions to improve it.

83. Open Site Explorer

http://www.opensiteexplorer.org/Link Research, Moz, Competitive Intelligence, Link Building
When Google and Yahoo started removing backlink data from the public, Moz built Open Site Explorer to fill a huge need. See backlinks, anchor text, popularity metrics and more.

87. Searchmetrics Visibility Charts

88. SEMrush

http://www.semrush.com/Tools Suite, Keyword Research, Competitive Intelligence
The paid and organic keyword data offered by SEMrush is often scary good and comprehensive. Also great for researching competitors' ads.

89. SERPmetrics

http://serpmetrics.com/flux/SERP Tracking, Competitive Intelligence
SERPmetrics flux charts track the flux for US search results across Yahoo, Bing and Google over a 30-day period. A paid API is also available.

90. SimilarWeb

http://www.similarweb.com/Competitive Intelligence
Impressive competitive intelligence across a number of online industries. Competitor website stats are hard to come by, but Similar Web does a good job.

91. StatCounter

http://statcounter.com/Analytics
Free, quick, and lightweight analytics solution. Often used by those who want to avoid using Google Analytics for privacy reasons.

92. Trello

https://trello.com/Productivity
Project management and tracking made simple. Used and endorsed by Moz.